Linking Electronic Bonding and Short-range Order to Strength in $\alpha$-Titanium Alloys: A First-Principles Study

Abstract

The development of accurate strength prediction models for titanium alloys is critical for advanced materials design. This study systematically examines how the mechanical properties of $\alpha$-Ti are affected by substitutional (X = Al, V, Mo) and interstitial (Y = H, C, N, O) alloying elements, with a focus on electronic bonding. Using density functional theory (DFT), we uncover the short-range ordering (SRO) of substitutional atoms and quantify their influence on the electronic bonding and mechanical behavior. The primary novelty of this work lies in developing a predictive model for tensile strength that goes beyond traditional empirical approaches. To quantify the contributions of individual solutes to strengthening, we use physically grounded quantum-chemical descriptors, such as the Integrated Crystal Orbital Hamilton Population (ICOHP), which is a direct measure of bond strength derived from first-principles calculations. The resulting formula quantitatively predicts the tensile strength of a wide range of $\alpha$-Ti alloys, demonstrating a significant advancement in the computational design of high-performance structural materials.